1. Check my current branch:

$ git branch

2. I use the $ git checkout -b dev to create a branch and switch to it:
   

The command $ git checkout -b dev is the same as the following two commands' integration:

$ git branch dev
$ git checkout dev

3. Check my current branch again:
   

   
   There is a * before the name of current branch.

4. Then I add Creating a new branch is quick. in my local test => readme.md
   

5. Check the status and operate the following command to commit the modified readme.md:

$ git add readme.md
$ git commit -m "branch test"

I add emoji here, $ git commit -m ":memo: branch test"

6. After these operation, I re-switch to master branch and check the local test => readme.md, find that the change I made has disappeared.
   

Because the change I made is on the dev branch, not the master branch. So I can't see it in current readme.md.

7. Now, merge the changes of dev to master branch:

$ git merge dev

8. Push the change to the remote repository：

$ git push

9. And now, I can delete the dev branch:

$ git branch -d dev

After deletion, check the current branch, that is only master branch.

10. Commands:

Check branches：git branch

Create a new branch：git branch <name>

Switch branches：git checkout <name>

Create+Switch branches：git checkout -b <name>

Merge branches：git merge <name>

Delete branches：git branch -d <name>